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In Snowmass, praise for ‘finest mastodon site in the world’

Paleontologist Kirk Johnson with the Denver Museum of Nature & Science talks at a press conference Thursday about the Snowmass Ice Age fossil site as Gov. John Hickenlooper and others listen. Pictured in the foreground are mastodon bones from the site.

SNOWMASS VILLAGE — Thousands of unearthed bones later, scientists and volunteers are heading home from Snowmass Village following an intensive 51-day excavation push at a world-class Ice Age fossil site.

But before things wrapped up, Gov. John Hickenlooper and a scientist from the Denver Museum of Nature & Science talked at a news conference in the village Thursday about the importance of the site and where things go from here.

Paleontologist Kirk Johnson, the excavation leader for the museum, said the site is particularly important for its proliferation of mastodon bones. Parts of at least 30 mastodons, juvenile and adult, have been found, and about 80 percent of the bones in total from the site come from mastodons.

“Without question this is the finest mastodon site in the world now,” Johnson said.

The fossils have been unearthed at Ziegler Reservoir, which is just outside the village and is being expanded due to municipal water needs. Construction worker Jesse Steele of Palisade found the first bone Oct. 14. Some 600 more were found last fall, and more than 4,800 more were removed this spring by museum staff and volunteers.

Work now will resume on the reservoir project, but Johnson said the reservoir water will help protect remaining fossils from oxygen and preserve them for possible further excavation in the future.

The bones of 26 different vertebrates have been found at the site. Among them are seven large mammals, which besides the mastodon include the giant bison, ground sloth, Columbian mammoth, deer, horse and camel. Bat, otter, muskrat, frog, bird, rabbit, beaver and other animal bones also have been discovered.

With many recovered fossils still not identified, Johnson thinks 30 to 40 different animals eventually might be represented in the collection.

This spring, on any given day about 50 people with shovels worked the site. Altogether, more than 230 museum staff, volunteers, interns, outside scientists and others were involved in this year’s excavation, and moved 8,000 tons of dirt by shovel.

“We worked that outcrop like ants on a hill,” Johnson said.

Crews focused on removing all of the fossil-bearing layer beneath what will be the site of the reservoir dam.

“We simply dug our way through this problem and dug all of the dirt out of the hole,” Johnson said.

A few museum representatives will remain this summer at the reservoir site, which has continued to yield more bones, including during Hickenlooper’s visit to the site Thursday. Hickenlooper also marveled at the layers of leaves still visible in peat that is tens of thousands of years old.

Researchers think some of the fossils date back 100,000 years or more. Their work now shifts to the museum, where they will carefully unpack and analyze bones to try to learn answers to questions.

“Over the next 12 to 18 months amazing things are going to come out of those plaster jackets,” Johnson said.

One question scientists hope to answer is exactly what caused the bones of so many animals to end up in the Ice Age lake. Johnson said the lake itself may have held dangers such as predators or steep walls that could have imperiled the animals.

Research also will focus on the Ice Age Rocky Mountain climate record that the site yielded. Previously no such record existed, and scientists had to extrapolate from evidence in places such as Greenland.

As far as changes go, Johnson said the fossil dig shifted the very direction of the museum.

“This is the largest discovery that the Denver Museum of Nature & Science has ever been involved with,” he said.

The museum, Snowmass Village and the Snowmass Water and Sanitation District are jointly working to raise $1.03 million to cover costs related to excavation, research, education and other activities, and more than half of the goal has been met.

Johnson and Hickenlooper praised the cooperation of the town, district and others in accommodating the dig, despite the challenges it presented.

Said Johnson, “Usually in these things somebody wants to fight somebody about something. Well, that just didn’t happen in this thing.”